We've all heard that weighing yourself once a day helps control weight, that you can lose 50 pounds in five years by walking a mile a day, or that people who eat breakfast are thinner. But as the New York Times points out, most of the weight loss theories we've heard don't actually have a lot of research behind them.

For example, take the idea that people who eat breakfast are thinner. What the studies have actually shown is that people who successfully keep weight off generally eat breakfast regularly—basically there's a correlation between keeping weight off and breakfast. The data has been misrepresented to mean something else entirely over time:

It is commonly thought, for example, that people who eat breakfast are thinner. But that notion is based on studies of people who happened to eat breakfast. Researchers then asked if they were fatter or thinner than people who happened not to eat breakfast—and found an association between eating breakfast and being thinner. But such studies can be misleading because the two groups might be different in other ways that cause the breakfast eaters to be thinner. But no one has randomly assigned people to eat breakfast or not, which could cinch the argument.

That said, the idea still makes sense, which is exactly why it gets spread:

As he delved into the obesity literature, Dr. Allison began to ask himself why some myths and misconceptions are so commonplace. Often, he decided, the beliefs reflected a "reasonableness bias." The advice sounds so reasonable it must be true. For example, the idea that people do the best on weight-loss programs if they set reasonable goals sounds so sensible.

The truth is, weight loss has a lot of ideas of the best way to do things, but few bits of evidence to actually prove what the best way to go about it is. The myths debunked by the researchers include:

That small changes in energy intake or expenditure produce large, long term changes (it doesn't).